Select ONE correct answer.

This excerpt is from “The Significance of the Frontier in American History (1893).”

Which part of the excerpt explains why Americans had reached the “end of the frontier?”

Since the days when the fleet of Columbus sailed into the waters of the New World, America has been another name for opportunity, and
which has not only been open but has even been forced upon them. He would be a rash prophet who should assert that
. Movement has been its dominant fact, and, unless this
, the American energy will continually demand a wider field for its exercise. But
. For a moment, at the frontier, the bonds of custom are broken and unrestraint is triumphant.

1 answer

"unless this condition of things does change, then"